Treasure islets: Pancreatic cells hold promise for diabetes

July 12, 2013
| by Nicole White

The Islets of Langerhans may sound like an exclusive tropical retreat, but they’re closer to home than you might think. These islets are found in the pancreas and hold precious treasures for researchers bent on finding cures for diabetes.

The Islets of Langerhans are clusters of cells in the pancreas, which include insulin-producing cells. In patients with type 1 diabetes, the immune system attacks and kills these cells. (Photo credit: Ivan Todorov)

Commonly referred to as islets, they’re clusters of cells in the pancreas, containing 1,000 to 3,000 cells each – resembling small islands in the pancreatic tissue. The average healthy, adult pancreas contains about 1 million islets, and they make up about 3 to 4 percent of the organ. As treatments for diabetes advance, these cells are becoming a focus of procedures lauded as potential keys to curing the disease.

The islets are named after Paul Langerhans, a German physician who discovered in them 1869. They include four major types of cells working together to regulate blood sugar, which is why they’re an important factor in diabetes.

The most plentiful are the insulin-producing beta cells and the glucagon-producing alpha cells. In diabetes, the immune system attacks the beta cells, destroying them. Diabetic patients cannot produce insulin, the hormone which lowers blood glucose levels.

Type 1 diabetes, or juvenile-onset diabetes, is an autoimmune disease in which the body’s own immune system destroys the insulin-producing islet cells. Insulin stimulates glucose uptake by the body’s cells, providing fuel for metabolic processes. Patients with type 1 diabetes produce little to no insulin, and must take insulin injections to survive.

One approach that has been investigated at City of Hope by the Division of Division of Molecular Diabetes Researchis islet cell transplantation. Pancreatic islets from donor pancreases are transplanted into patients during a one-hour procedure where a catheter is inserted through a tiny incision in the abdomen, which is numbed, and the cells are infused.

A section of a human pancreas showing islet cells in an image taken by Ivan Todorov, Ph.D., a research scientist in the Division of Diabetes, Endocrinology & Metabolism.

However, one drawback to this approach is that islets are rare – and it often takes at least two donor pancreases to harvest enough islets for treatment.

Donor pancreases are in such short supply only about 1 percent of those patients who would be eligible for islet cell transplantation are able to benefit from it. This is why researchers at City of Hope are working on developing islet cells in the lab that could supplement cells from donated pancreases.

Researchers are also seeking ways to improve existing islet cell transplantation methods, by establishing means to identify through gene signatures the highest quality islets for transplantation, investigating developing islets from stem cells to reduce the number of donor pancreases required for transplant and refining monitoring techniques for islet grafts using advanced technology and cellular imaging.

The green stain on this image of a human islet cell shows insulin, while the blue spots are the nuclei of the cells, stained for DNA. (Photo credit: Ivan Todorov)

Another approach researchers are exploring is mixed chimerism: This method would establish a mixed population of donor and recipient cells with in the bone marrow of the type 1 diabetes patient to "teach" the immune system not to reject newly-transplanted islet cells.